Aereo-stereo device



July 26, 1949. H. RANGER AEREO-STEREO DEVICE 2 Sheets-Sheet 1 Filed Aug. 16, 1944 July 26, 1949. R. H. RANGER AEREO-STEREO DEVICE 2 Sheets-Sheet 2 Filed Aug. 16, 1944 I I //vvE/vroz Par/74490 /7 P4/V6f1? Irroewa-y Patented July 26, 1949 UNITED STATES PATENT O FFICE AEREO-STEREO DEVICE Richard H. Ranger, Newark, N. J.

Application August 16, 1944, Serial No. 549,721

6 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment of any royalty thereon.

This invention relates to improvements in stereoscopic devices for determining the height of objects shown on aerial photographs.

It is a practice .in photogrammetry to make aerial photographs with a stereo-camera pointed downward at such angle that an accentuated and readily measurable element of elevation appears in the linear distance between the base of an object and its top in the resulting photograph, and to use a scale device to measure this difference on the photograph and thereby determine the actual height of the object. In this procedure,

theplane is required to fly at a given height when the picture is taken, so that the ratio between heights on the print and actual heights of the terrain and objects thereon will be as required.

If a continuous strip photograph is made by one of the modern cameras, .so operative, and particularly stereoscopic cameras producing continuous exposures through separate lenses on respective sides of a single film strip; and if the camera is pointed forwardly, and slightly to one side of the plane, two continuous .pictures side by side will be obtained, substantially as shown in Figure 1 of the drawings herein.

In the last mentioned type of camera, owing to the fact that the film is moved longitudinally in the camera at the same rate and direction that the projected image moves in the camera b reason of progress of the plane, the movement of the plane must be controlled so as to maintain a required speed, as well as its height maintained in coordination with the predetermined scale of measurements of linear distances on the print. These cameras and practices are well understood in the art, and need not be described in detail.

It is therefore an object of this invention to provide a device for producing a stereoscopic illusion by means of which the heights of objects appearing in aerial photographs can be quickly ascertained, and. to enable rapid mechanical graphic integration thereof while the film is being viewed in a stereoscopic viewer. At the same time it is sought to present means whereby the person viewing the film will be given an instant appreciation of the actual height measurements of objects seen in the stereoscopic image independently of the mechanical measuring device or other scale devices.

These and other objects are attained by the novel method and construction hereinafter described. and illustrated by the accompanying drawings, forming a part hereof, and in which:

Figure 1 is a perspective View of a stereoscopic device embodying the invention.

Figure 2 is a front elevational view of a section of the device.

Figure 3 is a view of grid screens used in connection with the device.

Figure 4 is a perspective view illustrating the stereoscopic illusion produced by the device.

Figure 5 is a side elevational View of the device, the angular difference in the planes of the mirrors being exaggerated for the purpose of illustration.

Figure 6 is a plan view of the device.

Figure '7 is a front elevational view of the device.

Referring to the drawings, the viewing device for producing stereoscopic illusions is shown to comprise an elongated flat bed plate 22, at the left end of which there is mounted an upper guide frame section I hingedly connected to a lower vertical guide section 2 erected on the bed 22. Attached to side frame pieces l2 of the lower section 2 there is a bar link 3 through which passes a clamping bolt 4, movable in an arcuate slot 5 in section I and having a clamp nut thereon to hold the section I in adjusted angular positions relative to the lower section 2. The section I is generally disposed in a plane at a very acute angle to the plane of the section 2, these planes meeting at a right horizontal line, as may be seen in Fig. 1. The section 2 may be slidably adjustable on the bed 22.

Forming a part of the upper section are two sheets of transparent structural material 6 and 1 or other transparent material at the rear and at the front respectively of the guide frame, spaced apart to receive the upper part of a picture sheet, which may be a band of photographic film or print 24 between them. Similarly, the lower section 2 has two spaced apart rear and front sheets of similar transparent material 8 and 9, to receive the lower portion of the same film positioned between sheets 6 and 1. The sheet 9 is slidable laterally on the base 23, and has fixed to v the lower portion thereof a lug l0, provided with a threaded aperture receiving a threaded bolt I I, passing through side member l2 of section 2, and having attached thereto a knob l3, havin a pointed projection M on the periphery thereof (Figures 1, 5, 6).

Images from film in the two sections are received in inclined mirrors I5 and I6, which have substantially the same structure, mounted at the and on a single film there will appear an upper picture A of terrain and a lower pictureBof. terrain, each of about 4% inches wide. However, due to the arrangement of the lensescof rthe camera the point of view of the lower picture is slightly ofiset from the point of view-oi the upper 'picture. This film is inserted in the deviceshetween the sheets of transparent material, withthe upper picture between sheets 6 and 1,:andthe4lower picture between sheets 8 and 9. The upper guide section I is inclinedslightly from the vertical toward the mirrors ['5 and 'l 6 which, for the particular picture strip indicated, "are positioned about inches from'the guide secztionsiand-thetwo mirrors are adjusted on their ball supports "so that Inasmuch as the grids and the photographs are in virtual contact with each other, it is possible to magnify these combined images as much as is desired. To this end, lenses have been placed in front of the photographs and practically any amountof magnification can be used and a correspondingiincrea'se in the mpcuracyajf' height determination canibe accomplished;

Semi-cylindrical plano-convex lenses, 5!! and 5| (see Figure 1), are preferred, as this type oflens enablesa broadsweepto be viewed. The lenses "are mounted on a frame so that they. can be moved-laterally simultaneously. The lenses are onemirror-will include a bundle of rays 'encompassing the image of the upper picture reflected 'toapoint-above, and the 'other mirrorwill similarly include the image of the lower 'picture -reflected-toa second pointabove, spaced Tromthe first point to-matchthe interpupillary distance of the eyes of the observer. 7

"In-Figure '3 are shown-diagrams of grids used in connection with the device. Oneofthese is marked on sheet 1 and another on sheet 3. The grids comprise "a plurality of parallel lines 3| crossed -by --a plurality of "diagonal lines 33 as shown, the parallel lines representing heights, 'andthe diagonal lines being -forthe purpose of facilitating the viewing and functioning of the parallel lines.

In operation, the film carrying the upperand lower pictures to be viewed is --inserted between -the"transparentplates of 'sectionsrl and '2, and 'fthe-grid on the lower section is madeto stereoscopicallyiuse with the grid of the upper section" by-turn'ing-the knob --'l 3 to move sheet!) I laterally. When the pictures'and grids are how viewed in the mirrors, each two-like groupsof the lines fof "the grids will appear to -be a three dimensional "figure above'the picture and-form-theappearance of jelly-like parallel"three-dimensional ridges 30, "36" and 3 9 of-diifereritheights and widths' asdndi'ca'ted in Figure 4 with lines 3-l indicating heights. The outside lines 32 of -the grid image appear to reston the ground' 'The pitch -o'f'-the threadson "the screw H is "such that each turn pfthescrew will move the'lower grid'agivemuriit of distance as indicated by thedn'dex69 on "the 'scaie- 68-in'Fig. 1. If the unit chosen be 'feet, then each revolution of the knob represents 50 feet of "height.

Now, to determine theheight of any object on V the picture, the film is moved until the object around appreciably.

mounted on the front sides of the sheets I and 9, and the-diagrams -(see Figure 4) are drawn on uthe-hack sides of the front transparent sheets, so that the diagramsjie close against the pictures. One 'oitheffronttransparent sheets is provided with a scaleGB and the.abutting sheet of the other guide section is provided with a pointer 69 to indi- '*cate the extent or lateral movementof one sheet "relative to the' other. r I

. a n'arrowzznetextending-entirely-across theunder- -'lyi-ng-pr'int. In-con' sequerrce also, I eally fused image of two gri'dswill "extend en- 'tirely-ac-rossthe stereoscopic imagefofterrainuerived by'viewing o'f the prints. Each grouppr net is successively smaller in the order name dffrom right to left so that a wide V-shaped ridge 30 is 'simul ated --a.-t-the*right, one 'iifl' "o'fless width'and altitude appears next, a narrow ridge "3 of the 'least'altitude appears at the-left "of the 'screenwork.

As a-result, when-the film'stripds 'moved progre'ssively through thegu'ides'whil-e being stereopsuggestionpf the actual height "or-the-objects' will be conveyed to the observer, accordingly "as the objects noted seem'to lie below or above the'apex or each ridge as the object passesithereund'er. -If

the lines ZZ-H have =-a un it spacing with "a scale measurement value of a unit oFheigh't, as ,the basejof each object reaches the base line 31 of the ridge after entering WHEYOIIB or the nets or grid 1 groups -34, *35, 36, fits height *may be read approximately b'y the number or such lin'es' 3l included in the principal vertical dimension of the obj ect inspected; Its appearance of '-height-in relation to the high, middle, 'orlow ridges '30, -31! 39";as it passes them, afiords'animmediate"indi- -cation -of the plosest' height represented in the griii groups. i

It will be seenthat the forms o'f'thefgrir'is .remove the need "for extensive shifting of --a picture to bring objects "in proper relation to indicia on measuring devices, as well as enabling immediate discernment of "approximate measur'ements since all obj ects pass under the groupshand lines by the simple sliding-ofthe'filminone direction'through "scope .as 'set "'forth'; in the "appended claims; For '75'examp1ehan'efiective' device can be provided by V the stereoscopiusing only one sheet of transparent material on the upper section and only one sheet on the lower section. Also, eiTective diagrams can be produced using diiferent arrangements of the lines.

The invention having been described, what is claimed is:

1. A stereoscopic device, comprising a lower picture sheet guide, an upper picture sheet guide, said guides meeting at a right line and being oblique to each other in planes at an acute angle to each other and constructed to receive commonly and slidably therethrough along said line a stereoscopic picture sheet, said guides each having front guide sheets of transparent material and rear guide sheets positioned to receive the picture sheet therebetween, similar diagrams of unequally spaced parallel lines on said front guide sheets arranged across the path of sliding movement of the picture sheet and normal to the principal linear height components of objects in the picture on the picture sheet, said parallel lines being spaced to indicate stereoptically a series of parallel ridges and valleys, means for moving one of the front guide sheets laterally relatively to the other front guide sheet, and means to project respective images from the portions of a picture sheet in the two said guides and of the superposed grids, to respective view points spaced an interpupillary distance apart.

2. The structure set forth in claim 1 further characterized by the diagrams having a plurality of rows of diamond shaped figures connecting groups of parallel lines, said groups respectively increased in width from one side to the other of the diagrams.

3. A stereoscopic device, comprising a first picture sheet guide, a second picture sheet guide, said guides being oblique to each other in planes at an acute angle to each other arranged to support respective sides of a picture sheet in said planes and constructed with an opening to receive a stereoscopic picture sheet slidably for movement therethrough with respective parts in said planes, front guide sheets for said picture sheet of transparent material in respective said guides, similar diagrams of unequally spaced parallel lines on said guide sheets spaced and arranged to indicate stereoptically ridges of successively different elevations and valleys across the path of sliding movement of the picture sheet, means for moving one of the front guide sheets laterally relative to the other and means to project images of pictures from respective side portions of a picture sheet in the guides and of the grids stereoptically.

4. In a photo-stereoscopic system for obtaining measurements of specific objects on terrain photographed by aerial photography wherein cooperative calibrating stadia devices are imposed respectively upon pictures being stereoscopically viewed, and measurements obtained by calibrating devices; that improvement which comprises an aerial stereoscopic picture strip having its principal field axes disposed at a substantial angle to the vertical elements shown in the pictures on the strip, a support for the strip constructed to receive the strip slidably through the support, means to enable stereoscopic inspection of pictures displayed therein, said calibrating devices comprising two grids carried by said support positioned to lie superposed upon respective pictures on the strip in said support, each grid having parallel rectilinear lines thereon extending the full dimension of the respective picture transverse to the direction of its said vertical elements in the picture, and variously spaced in groups, the lines in each group being mutually arranged to simulate stereoptically a ridge when viewed with its corresponding group of the other grid, the ridges so simulated being parallel and of progressively increased heights in one direction along the path of movement of the picture strip in said guides.

5. The structure of claim 4 wherein said lines are distinguished in a plurality of groups, of respective different widths, each having a width significant of a respective height when the grids are stereoptically fused over the prints, said grids having lines crossing the said parallel lines of a group in a direction to create the semblance of respective three-dimensional ridges for each of said groups when the grids are stereoscopically fused over a print, each said ridge extending entirely across the stereoscopic image, having its base at the apparent ground level of said image and its apex in space at a respective height between the print and the observer.

6. The structure of claim 4, wherein said lines are distinguished in at least one group having a width related to a respective height when the grids are stereoscopically fused over the prints, said grids having diagonal lines crossing the said parallel lines of each group and extending from each side of the group in a direction to create the semblance of a three-dimensional ridge extending across the print having its base at the apparent ground level and its apex in space between the observer and the prints.

RICHARD H. RANGER.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 583,703 Grousilliers June 1, 1897 907,973 Crocker Dec. 29, 1908 934,916 Von Hofe Sept. 21, 1909 1,494,728 Beyerlein May 20, 1924 1,743,952 Barr et a1 Jan. 14, 1930 1,816,181 Eliel July 28, 1931 1,894,148 Barr Jan. 10, 1933 FOREIGN PATENTS Number Country Date 164 Great Britain 1879 466,263 Great Britain May 25, 1937 

